Short peptide constructs mimic agonist sites of AT(1)R and BK receptors
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2013-03-01
Autores
Lopes, Douglas Duarte [UNIFESP]
Vieira, Renata de Freitas Fischer [UNIFESP]
Malavolta, Luciana [UNIFESP]
Poletti, Erick Fernando [UNIFESP]
Shimuta, Suma Imura [UNIFESP]
Paiva, Antonio Cechelli de Mattos [UNIFESP]
Schreier, Shirley
Oliveira, Laerte [UNIFESP]
Nakaie, Clovis Ryuichi [UNIFESP]
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Extracellular peptide ligand binding sites, which bind the N-termini of angiotensin II (AngII) and bradykinin (BK) peptides, are located on the N-terminal and extracellular loop 3 regions of the AT(1)R and BKRB1 or BKRB2 G-protein-coupled receptors (GPCRs). Here we synthesized peptides P15 and P13 corresponding to these receptor fragments and showed that only constructs in which these peptides were linked by S-S bond, and cyclized by closing the gap between them, could bind agonists. the formation of construct-agonist complexes was revealed by electron paramagnetic resonance spectra and fluorescence measurements of spin labeled biologically active analogs of AngII and BK (Toac(1)-AngII and Toac(0)-BK), where Toac is the amino acid-type paramagnetic and fluorescence quencher 2, 2, 6, 6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid. the inactive derivatives Toac(3)-AngII and Toac(3)-BK were used as controls. the interactions characterized by a significant immobilization of Toac and quenching of fluorescence in complexes between agonists and cyclic constructs were specific for each system of peptide-receptor construct assayed since no crossed reactions or reaction with inactive peptides could be detected. Similarities among AT, BKR, and chemokine receptors were identified, thus resulting in a configuration for AT(1)R and BKRB cyclic constructs based on the structure of the CXCR4, an alpha-chemokine GPCR-type receptor.
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Amino Acids. Wien: Springer Wien, v. 44, n. 3, p. 835-846, 2013.